LRC - Load Response Control for Alternators ...What is it???

From what I've read so far, my understanding is that it gradually increases the alternator output to maximum over a period of seconds to reduce the torque load the alternator puts on the engine.
Is this how it works?

Also, wouldn't an LRC device prevent an alternator from providing short high amperage bursts in the case of a high powered stereo installation with fast hard hitting bass?

A load control system for controlling the field current of an alternating current generator (alternator) and the idle speed control system for the engine that drives the alternator. A voltage regulator senses the output voltage of the alternator and controls field current by causing a semiconductor switch connected in series with the field winding to switch on and off in accordance with the magnitude of the sensed voltage. The voltage regulator is controlled to operate in a conventional manner when engine speed is higher than engine idle speed. When engine speed is in an idle speed range the duty cycle or on time of the semiconductor is controlled such that consecutive occurring on times are gradually increased to gradually increase field current when the output voltage of the generator is below a desired regulated value. The system operates to actuate an engine idle speed control system to increase the amount of fuel-air mixture supplied to the engine when the on times of the semiconductor switch are being gradually increased. In the event that engine speed decreases by a predetermined amount when the engine is operating in the idle speed range the on time or duty cycle of the semiconductor switch is reduced to a minimum to prevent engine stall.

Now with that said for high power stereo installs you have 2 options to premature alternator failure and make your system stand up to abuse.
1) install a second battery to cope with the ampage draw
2) install a capacitor to lower the direct draw from your battery

Capacitors are what I usually go with due to the compact size and ease of install. They help to cushion high draws on the system and also make for better overall amp performance. 1 Farad for ever 1000watts is a general rule ppl use but I like to go with 1 farad capacitors for every 500 watts of power you are going to be using. Make sure that you also opt for proper sized wiring for the power you want to put out. So in other words 8 gauge power wires wont supply a 2000 watt system properly. Bigger wire = less resistance and can provide more ampage. for a 1000 watt plus system I opt for 4 gauge as the smallest wire to be used for power and ground. Make sure that you match both (same size wire for both) also beef up your battery to chassis ground wire with the same gauge. All exterior connections should be soldered and shrunk tubed or molex connections. I solder and shrink tube all electrical work to ensure a good solid connection. Also use dielectric grease on all grounds and power connections that are exterior of the cabin. If you are not familiar with the rules for electricity then I recommend that you learn the basics. For a 12 volt system to put out 1000 watts that is (Watts=AmpageXVoltage) 83.33 Amps of draw, most alternators top out at 80 amps. So do the math. You will need a capacitor to help that out.

150 amps from the alternator would probably require almost 3 horse power from your engine wouldn't it? Seems like it would be kinda weird if every time the base hit you instantly lost 3 HP. Might feel like driving through a bunch of small puddles or something. The battery can instantly provide the power can't it? I know that the battery voltage alone is not quite as high as the voltage you get from the alternator though.

I've heard that for every 25 amps, you need 1 HP to drive the alternator.
I don't know how true that statement is though.
In theory, that means that the alternator would need 6 HP at 150 amps, or fully loaded at 200 amps needs about 9 HP to drive it.

The battery can "instantly" provide power per se, but due to it's internal resistance, there is a slight delay which is why people use capacitors to fill in the gap between the microseconds between the demand and delivery from the battery.

But keep in mind, that the voltage potential of a fully charged battery is about 12.9 volts, so unless the system voltage drops below that point, the alternator is supplying all of the power from 13 volts and up. Above 12.9 volts, the current is trying to flow INTO the battery, not out.

If the function of LRC is to ramp up the alternators current output gradually over a period of seconds, I'm thinking it may allow the system voltage to dip below 13 volts when a bass note hits and start drawing from the battery.

As a result of the voltage drop the output from the amp also drops. Amps are rated at 14.4 volts, so at 13 volts they only put out 90% of their power.

Another note about capacitors, is that you need to know their voltage rating, and their farad capacity. Divide the farad rating by the voltage rating. That will tell you how many farads per volt you have to work with. My understanding is that a farad is 1 amp per volt.

So if an 18 farad cap is rated at 18 volts, and is charged up to 14 volts, it can throw out 1 amp before dropping to 13 volts. Assuming my system draws 150 amps, the capacitor is only a factor for 1/150th of a second.

in laymens terms it means that when there is a higher demand on the alternator it tries to match it and when its low demand it puts out low current/voltage. The response time to the demand depends on the alternator and the sensitivity of the lrc.

in laymens terms it means that when there is a higher demand on the alternator it tries to match it and when its low demand it puts out low current/voltage. The response time to the demand depends on the alternator and the sensitivity of the lrc.

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So a 2.5 or 10 second LRC means it will delay full output by 2.5 or 10 seconds respectively?

Adding an LRC regulator is like adding shock absorbers to a car that never had them, but at practically no increase in cost. The benefits are smoother engine idling and longer drivetrain life. LRC is designed into the voltage regulator and is transparent to the vehicle.

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and this probably answers my question about skipping LRC

Without LRC, the sudden 20-amp load caused by the radiator fan kicking in would jerk the engine due to the alternator load. With LRC the alternator load is applied smoothly, giving the ECU a chance to readjust the engine speed.

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Now the question is, there is 2.5 second LRC and 6 second LRC units. Which is better?

in laymens terms it means that when there is a higher demand on the alternator it tries to match it and when its low demand it puts out low current/voltage. The response time to the demand depends on the alternator and the sensitivity of the lrc.

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So a 2.5 or 10 second LRC means it will delay full output by 2.5 or 10 seconds respectively?

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That is my understanding as well, and it's the voltage regulator that determines that (I.E. - you can sometimes opt buy a voltage regulator with a shorter delay if you want to)